docs: def compute_transformed(context):
      """Compute transformed key for opening database"""
  
      if context._._.transformed_key is not None:
          transformed_key = context._._transformed_key
      else:
          transformed_key = aes_kdf(
              context._.header.value.dynamic_header.transform_seed.data,
              context._.header.value.dynamic_header.transform_rounds.data,
              password=context._._.password,
              keyfile=context._._.keyfile
          )
  
      return transformed_key